1. Field of the Invention
The present invention generally relates to a liquid crystal display apparatus and to a method therefor, and more specifically the present invention relates to the control of the backlight in a liquid crystal display apparatus.
2. Description of the Related Art
Recently, liquid crystal display apparatuses are used in personal computers, workstations, TV sets, etc. A liquid crystal display apparatus allows either still or moving images to be displayed on a liquid crystal display panel by scanning the liquid crystal display panel in accordance with video signals. The video signals include image data carrying information regarding images to be displayed, and synchronization data which allow synchronous scanning of the liquid crystal panel so as to form images thereon.
The liquid crystal display apparatus, in order to provide brighter images, typically incorporates a backlight on the rear surface of the liquid crystal panel thereof. The backlight is driven by, for example, an inverter circuit, and emits light on the liquid crystal panel from the rear surface thereof. As a light source for the backlight, cold-cathode tubes, which are compact and efficient, may be employed as can conventional fluorescent tubes.
The liquid crystal display apparatus does not have a very rapid response to video signals. Therefore, there is a problem in that trailing of images occurs when moving images are displayed, degrading picture quality.
Accordingly, it is an object of the present invention to provide a liquid crystal display apparatus and method in which trailing of images is prevented and picture quality is thus improved.
To this end, the present invention, in one aspect thereof, provides a liquid crystal display apparatus having a display control unit for processing video signals; a liquid crystal module, controlled by the display control unit, for displaying an image thereon; a backlight unit for emitting light from a rear surface of the liquid crystal module; a vertical synchronization signal processing unit for generating pulse signals based on vertical synchronization signals of the video signals, the pulse signals being pulse-width modulated and in synchronization with the vertical synchronization signals; and an inverter unit for generating, at a predetermined oscillation frequency, voltages for driving the backlight unit based on the pulse signals.
The present invention, in another aspect thereof, provides a display method for displaying an image on a liquid crystal module in accordance with video signals. The display method includes the steps of generating pulse signals based on vertical synchronization signals of the video signals, the pulse signals being pulse-width modulated and in synchronization with the vertical synchronization signals; generating voltages based on the pulse signals at a predetermined oscillation frequency; and driving, with the voltages, a backlight unit for emitting light from a rear surface of the liquid crystal module.
With these features, the backlight is controlled based on the pulse signals which are in synchronization with the vertical synchronization signals. The backlight is turned off while the liquid crystal module is being scanned for an image of the next field to be displayed, and is turned on when the scanning is complete and the liquid crystal module is ready to display the refreshed image. Accordingly, afterimages such as trailing, which tend to arise for moving images, do not appear, and picture quality is thus improved.